Clear method to clear the queue

[BrendanSimon]

I have created a clear() method in a sub-class to clear a persistent queue.

Is there a better approach than getting entries in a loop?

Feature request: add a clear method upstream :)

from persistqueue import (
    Queue as PersistQueue,
    Empty as PersistQueueEmpty,
    Full as PersistQueueFull,
    )

class MyPersistQueue(PersistQueue):
    """
    Customised persistqueue.Queue
    """

    def clear(self) -> None:
        """
        Clear all items from queue.

        persistqueue.Queue does not have a native `clear()` method.
        """

        while True:
            try:
                self.get_nowait()
            except PersistQueueEmpty:
                break

[brendan-simon-indt]

This might be an error in the clear() method, which does not call self.task_done()

[brendan-simon-indt]

Adding self.task_done() did not help clear the error in issue #236.
I had to remove the persistqueue directory path to resolve the issue.
#236 (comment)

[peter-wangxu]

did you have a try reading the queue from new queue?

[brendan-simon-indt]

When my app/service starts up, a new thread is created and during its initialisation it creates the PQ.
I specify the temppath as a subdirectory of the pq path.

The purge queue keeps a list of filenames to delete, when new filenames are added and the queue is full (i.e. get filename, delete file, add new filename)

I clear the PQ and repopulate. The clear function does get_nowait() in a loop until it is empty.
Then I repopulate the queue from saved files in a directory.
NOTE: I could use smarter logic so that it only does this when the queue is first created. e.g. if the queue is empty.

        pq = self.purge_queue
        if pq is None:
            #! --- create persistent purge queue ---
            pq_path = self.save_path / 'purge_queue'
            temppath = pq_path / '_tmp.d'
            temppath.mkdir(parents=True, exist_ok=True)
            pq = MyPersistQueue(path=str(pq_path), tempdir=str(temppath), maxsize=purge_maxsize, serializer=cbor2)
            
            #! --- cleanup any extraneous/residual save files ---
            pq.clear()
            #! --- grok existing saved files and place filesnames in pq ---
            ...

            self.purge_queue = pq